53 Pa. Stat. § 25893
This department shall consist of no less than five (5) members, and an additional member for each seventy-five thousand inhabitants over two hundred thousand as shown by the last preceding United States decennial census, all of whom shall have been residents of the city, or of adjacent territory annexed to the city, for at least ten years, and shall not be of the same political party. The annual salaries of such members shall be fixed by the council: Provided, That such salaries shall not be less than fifteen hundred ($1,500) dollars per annum for the first two hundred thousand inhabitants of said cities, with an additional five hundred ($500) dollars per annum for each additional seventy-five thousand inhabitants, according to the last preceding United States decennial census; and said members shall, from time to time, make all valuations for purposes of municipal taxation.
53 P.S. § 25893